Quote: Originally Posted by sup3rsprt
Once a product key is activated it then corresponds to a PID which is composed of various things like the current hardware installed in the computer. If you keep installing it on the same computer there is no problem. But when you start using that key on another machines it will probably work a few times but eventually you'll run out of activations and be forced to call Microsoft. This prevents the same product key from being circulated and used by everyone on the internet.
The "PID" key is a unique numeric identifier for each hardware componenet in your PC. Its like a "VIN" on your car. you may have 2 identical Camaros down to the last detail but they will always be identified by the VIN that comes with the vehicle.
its exactly the same with the PID and the way the Windows 7 installation works is it records the PID of your current computer where you are installing the New OS.
Now your system will trigger an Activation Verification if you make any hardware changes that would go past a particular "threshold". That threshold is currently set at 80% and Microsoft has assigned each hardware components corresponding values:
Processor and MOBO 70%
Ram and Graphics is 10% each
Obviously changes on your computer for the above mentioned parts that goes past 80% will trigger the activation.
Ergo if you install Windows 7 on a second computer even if the setup is completely identical to the first computer the unique PID will trigger the activation.